media: microchip: don't set bus_info

Let the V4L2 core fill this in.

Fixes these compiler warnings:

drivers/media/platform/microchip/microchip-isc-base.c: In function 'isc_querycap':
drivers/media/platform/microchip/microchip-isc-base.c:486:28: warning: '%s' directive output may be truncated writing up to 35 bytes into a region of size 23 [-Wformat-truncation=]
  486 |                  "platform:%s", isc->v4l2_dev.name);
      |                            ^~
drivers/media/platform/microchip/microchip-isc-base.c:485:9: note: 'snprintf' output between 10 and 45 bytes into a destination of size 32
  485 |         snprintf(cap->bus_info, sizeof(cap->bus_info),
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  486 |                  "platform:%s", isc->v4l2_dev.name);
      |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/media/platform/microchip/microchip-isc-base.c: In function 'isc_mc_init':
drivers/media/platform/microchip/microchip-isc-base.c:1996:76: warning: '%s' directive output may be truncated writing up to 35 bytes into a region of size 23 [-Wformat-truncation=]
 1996 |         snprintf(isc->mdev.bus_info, sizeof(isc->mdev.bus_info), "platform:%s",
      |                                                                            ^~
drivers/media/platform/microchip/microchip-isc-base.c:1996:9: note: 'snprintf' output between 10 and 45 bytes into a destination of size 32
 1996 |         snprintf(isc->mdev.bus_info, sizeof(isc->mdev.bus_info), "platform:%s",
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1997 |                  isc->v4l2_dev.name);
      |                  ~~~~~~~~~~~~~~~~~~~

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>